A review of near-infrared laser protective dyes

Due to the requirement of near-infrared laser protective dyes and laser stealth materials, this review focused on the research progress of near-infrared absorbing dyes, and some suggestions were put forward on the future research. Some of the most important technical requirements for laser-protective dyes within the plastic are as follows: sharp absorption bands at specific wavelengths corresponding to laser emission, excellent lightfastness, robust thermal and chemical stability, stability to ambient conditions, high optical density and scotopic luminous transmission, good solubility in plastic and low toxicity. This review paid attention to the properties such as the maximum absorption wavelength and the absorption intense, attention had been directed towards eight types near-infrared dyes: cyanine dyes which included polymethine dyes and squarylium or croconium dyes, phthalocyanines and naphthalocyanines, metal complex dyes, quinone dyes, azo dyes, radical dyes, multiphenylmethane dyes and perylene dyes. Other kinds of near-infrared dyes were also mentioned, such as aromatic annulenes, planes containing so-called nonbenzenoid aromatic rings, cyclic cross-conjugated hydrocarbons having inserted p-quiniod ring, fluorenylium dyes with inorganic anions, donor-acceptor cyclophanes, tetrapyrazinoporphyrazines and pentaazadentate expanded porphyrins et al. All of the dyes mentioned above had some good properties for use as the near-infrared laser protective dyes and laser stealth materials, but there also existed defects in every kind of dyes.